In the course of his current media tour flogging his new book, a dramatic account of his Naderesque battle against heart disease, former vice-president Dick Cheney is keeping up with one exercise that probably really has helped keep him alive: saying what he wants and not caring what anyone thinks.

Asked on Monday by CNN's Jake Tapper why the United States spies on its allies, Cheney said he would not acknowledge that any such spying happened – but “you never know what you’re going to need.”

"We do collect a lot of intelligence," Cheney told CNN. "Without speaking about any particular target or group of targets, that intelligence capability is enormously important to the United States, to our conduct in foreign policy, to defense matters, economic matters, and I'm a strong supporter of it."

NSA surveillance on foreign leaders appears to have grown under Cheney’s tenure, which also saw a flowering of illegal domestic spying. An NSA document dated October 2006, leaked by Edward Snowden and obtained by the Guardian, said hundreds of phone numbers connected with 35 world leaders had been "tasked."

"We are vulnerable, as was shown on 9/11, and you never know what you're going to need when you need it," Cheney told Tapper.

The notion that more spying is always better has been challenged not only by privacy advocates but also by analysts who argue the payoff isn't worth the costs – or the risks. Whatever their reliance on US intelligence, leaders in Europe and South America are projecting anger at revelations of the extent of US surveillance. The state-owned Deutsche Telekom has called for the creation of a discrete German internet space, inviting concerns about the cohesion of the "worldwide" web.

According to former deputy commerce secretary David Rothkopf, Clinton officials asked themselves: "Is the intelligence we might be gathering worth the risks entailed by getting it?" The answer was no, Rothkopf wrote last week in Foreign Policy, where he is editor-at-large:

I acutely remember a very uncomfortable meeting with a number of very senior-level officials in which this question was raised about economic intelligence in particular. The conclusion of the intelligence official in attendance was that it was not.

Rothkopf points out that the surveillance tools available in the digital age carry vulnerabilities in proportion with their apparent powers.

While he is an unstinting critic of the current administration, Cheney does find the occasional Obama policy he likes. In February he said the drone assassination program is "a good program."